Method and an apparatus for cutting free and removing the rectum of a carcass of a slaughtered animal, preferably pigs

ABSTRACT

A method of cutting free and removing a rectum of a carcass of a slaughtered animal hanging by the hind legs with a head downwardly. An apparatus including a rotating tubular knife is positioned in the vicinity of the rectum of the carcass. A guiding pin on the apparatus is inserted into the rectum of the carcass coaxially with a main axis of the rectum. The guiding pin is arranged coaxial with the rotating tubular knife. The rotating tubular knife is moved into the carcass coaxially with the main axis of the rectum, thereby cutting the rectum free of the carcass. The rectum is retained in the rotating tubular knife. The rectum is pulled free of the carcass toward a ventral side of the carcass in a direction substantially perpendicular to a main axis of the carcass. The rectum is hung downwardly over a side of a protective shield. The side of the shield faces away from the carcass.

FIELD OF THE INVENTION

The invention relates to a method of cutting free and removing therectum of a carcass of a slaughtered animal, preferably a pig hanging onthe hind legs with the head downwards, whereby the rectum is cut free bymeans of a rotating tubular knife being moved into the carcass from theback substantially coaxially with the center line of the rectum whilebeing guided by means of a pin inserted in the rectum after being cutfree, the rectum is retained by the knife and, thereby, pulled out ofthe carcass. The invention also relates to an apparatus for carrying outthe above method.

BACKGROUND OF THE INVENTION

It is known, from DK-PS No. 156,808, to cut free the rectum, theso-called fatty end, of a carcass of a slaughtered animal by means of arotating tubular drill or a rotating tubular knife, where the knife isplaced opposite the rectum of the carcass in such a manner that the axisof rotation of the knife is placed in extension of the center line ofthe rectum and the spine of the carcass. Subsequently, the rotatingdrilling pipe is moved forward. The movement by the drill is guided by apin placed in the tubular drill and inserted in the anus. According toDK-PS No. 156,808, the drill is removed after the cutting procedure.

Attempts at pulling out the rectum in extension of the center linethereof are also known, for example, DK-PS No. 129,495, in the rectum isretained outside the animal on the back of the carcass while theremaining intestinal portions are cut free. A condition for pulling outthe rectum in extension of its center line is that the rectum is soresilient that it can be kept intact outside the carcass. It turned out,however, that the resilience of the rectum varies much from animal toanimal, especially in connection with pigs. As a result, the rupture ofthe rectum often arises, particularly with sows.

Both when the rectum is left inside the carcass after the cuttingprocedure and when attempts are made at pulling out the rectum wherebythe rectum ruptures, a risk exists of the visceral contents sieving outinto the meat and thereby contaminating the meat. Contamination causedby sieving visceral contents in the latter process turned out to presentsevere problems of bacteria, such as Salmonella and Yersenia, inconnection with meat from the bacon factories. Accordingly, theimportance of avoiding in any possible way a sieving of visceralcontents is recognized. The rectum cut free cannot therefore be leftfree in the carcass after the cutting free procedure. Nor should ruptureof the rectum be allowed during attempts to pull it backwards relativeto the hind part of the carcass and retain it in the drill until theremaining portion of the intestinal portions have been cut free.Although the remaining intestinal portions are cut free without causingany sieving of the visceral contents, a risk exists that some of thevisceral contents nevertheless escape in connection with releasing therectum from the drill.

SUMMARY OF THE INVENTION

Accordingly, it is the object of the invention to provide a method that,in a highly reliable manner, avoids all allowing contaminating visceralcontents to escape during the slaughtering procedure.

The method according to the invention is characterized in that therectum cut free is pulled out of the carcass in a directionsubstantially perpendicular to the length axis of the carcass towardsthe ventral side of the carcass while the ham is cut in two, in order toallow the rectum to be pulled forwards onto the ventral side. The rectumis subsequently left hanging downwardly over a side of a protectingshield facing away from the carcass.

This method avoids subjecting the rectum to a tension, which it cannotoften stand up. In addition, the rectum is carried downwardly and lefton a location where the visceral contents cannot come into contact withthe carcass or the slaughterman. During the pulling out movement, theattachments usually resisting the pulling out of the rectum in arearward direction are easily torn loose without thereby tearing apartthe rectum.

The apparatus for carrying out the method comprises a tubular rotatableknife coaxially surrounding a pin and comprising a cutting edge at thefront end. The rear end of the knife opposing the cutting edge isprovided with means for providing a vacuum suction.

The apparatus according to the invention is characterized in that thepin is stationary, and that the inner side of the tubular knife and theouter side of the pin are provided with a thread being cut in oppositedirections.

The resulting apparatus reliably ensures that the rectum will be cutfree and retained during the pulling out movement because oppositelyoriented threads on the rotating knife and the stationary pin pull therectum in an efficient manner into the interior of the apparatus. Therectum is retained in the interior partly by means of a vacuum andpartly by the engagement with the threads during the forward pulling tothe protecting shield. The threads must, of course, be of such a shapethat they do not tend to cut a hole in the rectum.

According to the invention, the inside shape of the tubular knife mayhave a conical transition portion narrowing away from the cutting edgeand continuing into a cylindrical portion carrying the internal thread.The resulting squeezing of the rectum about the pin is very reliable atthe same time as the effect of the vacuum is efficiently supported. Thevacuum effect is additionally supported in an advantageous manner by thepin according to the invention being shaped with a conical transitionportion expanding away from the free end of the pin and continuing intoa cylindrical portion carrying the external thread.

Finally according to the invention, a fixed knife may be providedoutside the tubular rotatable knife. The fixed knife automatically cutsthe ham while the rectum, after being cut free, is being pulled outtowards the ventral side of the carcass. Before the described apparatusis used, the abdomen of the carcass has been cut up in a conventionalmanner, and the carcass has been opened up to the inguinal bone, whichhas preferably also been cut through before the apparatus is used. Afterthe rectum has been cut free, the ham need only be cut in two in orderto allow the rectum to be pulled forwards onto the ventral side whilebeing retained by the apparatus. The latter procedure is carried out inan easy and fast manner by means of the fixed knife. If desired, theinguinal bone can be cut simultaneously with the above procedure becausethe bone comprises a relatively easily cutable cartilage portion in thecenter thereof. The latter cutting requires, however, rather skilledslaughtermen.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in greater detail below with reference to theaccompanying drawings, in which

FIG. 1 is a diagrammatic view of a carcass of a slaughtered animal, thecarcass being slung in the hind legs ready for having the rectum cutfree in accordance with the present invention by means of a preferredembodiment of the apparatus according to the invention, one hind leg ofthe carcass is omitted for the sake of clarity;

FIG. 2 is a diagrammatic sectional view on a larger scale of a portionof the carcass during the cutting free of the rectum, only part of theapparatus for cutting the rectum free is diagrammatically shown, partlyin section;

FIG. 3 corresponds to FIG. 2, but shows a method during the forwardpulling of the rectum on the ventral side of the carcass; and

FIG. 4 is an axial, sectional view on a larger scale through theapparatus of FIG. 1, whereby parts have been omitted for the sake ofclarity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The carcass of a slaughtered animal shown in FIG. 1 is a pig 1 ready forbeing subjected to a cutting free of the rectum. The abdomen of thecarcass has been cut up in advance and opened to the inguinal bone 2,indicated by a dotted line in the drawing. The cutting free of therectum is carried out by means of an apparatus 3 described in greaterdetail below. The apparatus 3 is connected to a hose 4 for the feedingof vacuum, pressurized air, hot water, and cold water, a hose 5 forpressurized air, as well as an electric wire 6. The apparatus 3 is slungin a line 7 being unwound from a storing spool 8. A mirror 9 is providedbehind the carcass, opposite the hind portion of the carcass. The mirroris used by the slaughterman during the handling of the apparatus 3.

The rectum of the pig 1 is cut free opposite a platform 15 of such aheight relative to the pig that the slaughterman can cut the rectum freeat chest height. A protecting shield 10 is provided between theslaughterman and the pig 1. The shield extends obliquely downwards froma guide pipe 11 and comprising a drain 12 at the bottom.

Before the method according to the invention is initiated, the pig 1,slung in its hind legs, has been subjected to a slaughtering processending with a cutting up of the abdomen, cf. the reference numeral 13 inFIGS. 2 and 3. The abdomen of the pig 1 slung up has been cut to the ham14 between the hind legs of said pig, the ham abutting the rectum of thepig. In addition to the cutting of the abdomen 13, the inguinal bone 2is also cut.

Subsequently, the cutting free of the rectum is initiated by means ofthe apparatus 3. As shown in FIG. 4, the apparatus comprises a carryingframe 15 carrying an air motor 16 at one end. The air motor is adaptedto be driven by means of pressurized air fed through the hose 5, cf.FIG. 1. The air motor 16 comprises an output shaft 17 carrying a toothedpulley 18 arranged in the interior of the carrying frame 15. A toothedbelt 19 extends about the toothed pulley. The toothed belt extendsthrough the carrying frame 15 to the opposite end of the frame where itengages a driven toothed pulley 20. The toothed pulley 20 is permanentlyconnected to a rotor 22 by means of a key 21. The rotor is rotatablyjournalled inside a substantially cylindrical bearing housing 23 bymeans of ball bearings 24 and 25. The bearing housing 23 is supported byand permanently connected to the carrying frame 15 in a manner notdescribed in greater detail.

The bearing housing 23 is closed at one end by means of a cover 26. Thecover 26 is centrally fixedly connected to a hollow shaft 27 coaxiallyextending through the rotor. The shaft 27 comprises at the end adjacentthe cover 26 an internal thread 28 for the securing of the hose 4 forvacuum, pressurized air, and hot and cold water. The hollow shaft 27extends, as mentioned, coaxially through the rotor 22 and is connectedby means of an external thread to a stationary pin 30 arranged insidethe apparatus. The pin 30 comprises an inner tubular part 31 of acircular cross section and with a through hole 32 provided with aninternal thread. The inner part 31 of the pin, is at the inner end,screwed onto the hollow shaft 27 by means of the latter thread. Theopposite end of the inner part is closed by means of a second, outerpart 33 in the form of an annular solid bar provided with an externalthread, which is to engage the thread in the through hole 32. The outerpart 33 is smoothly rounded at the free end facing away from the innerpart 31.

A tubular knife 34 is provided coaxially about the pin. The knife is, atone end, screwed fixedly onto the rotor 22 by means of co-operatingthreads 35. The tubular knife 34 carries a circular cutting edge 36 atthe end opposite the rotor.

A free, rotationally symmetrical passage is provided about the pin 30from the free end of the pin 30 and past the inner part of the pin tothe portion of the hollow shaft 27 adjacent the pin 30. The latterportion of the hollow shaft 27 is surrounded by an inner circumferentialrecess 38 in the rotor 22. The bottom of the recess is closed by meansof a gasket 39 sealingly abutting both the hollow shaft 27 and the rotor22.

Openings 39, 40, 41, and 42 are provided opposite the interior of thepassage 37 about the pin 30 in the area about the recess 38 in the rotor22. The openings perforate the wall of the hollow shaft 27 and formthereby an open connection to the interior of the hollow shaft 27 andconsequently to the hose 4.

The tubular knife 34 is, at the end abutting the cutting edge 36,internally shaped with a cylindrical portion 43 abutting an area 44which narrows conically to an inner cylindrical area 45 shaped with aninternal thread 46. The outer part of the pin is of a circular crosssection and extends substantially parallel to the inner cylindrical area43 of the tubular knife 34 until the cylindrical area 43 abuts theconical area 44. The outer end of the inner tubular part 31 of the pin30 is situated at about the same position as the conical area 44. Theouter end of the inner tubular part 31 of the pin 30 comprises aconically shaped area 47 of substantially the same axial extent as theinner conical area 44 of the tubular knife 34. The conical area 47expands inwardly and continues into an inner cylindrical area 48 ofalmost the same axial extent as the inner cylindrical area 45 on thetubular knife 34. The inner cylindrical area 48 on the pin 30 is shapedwith an external thread 49.

The thread 49 on the pin 30 is cut in opposite direction relative to thethread 46 on the inner side of the tubular knife 34.

A plane knife 51 is secured on the outer side of the bearing housing 23by means of a substantially radially projecting bracket 50. The planeknife 51 extends substantially parallel to the axis of the tubular knife34 a suitable distance forwards to the vicinity of the cutting edge 36thereof.

When the apparatus 3 is running, the rotor 22 is caused to rotate bymeans of the motor 16 through the toothed belt 19, and consequently thetubular knife 34 is also caused to rotate. The pin 30 coaxially arrangedinside the tubular knife 34 remains stationary. The free end of the pinprojects slightly outside the cutting edge 36 of the knife 34.

A handle 52 is provided for facilitating the handling of the apparatus3. The handle comprises switches, not shown in greater detail, for thecontrol of the running of the motor 16 and the feeding of vacuum,pressurized air, hot or cold water to the interior of the hollow shaft27 through the hose 4.

When carrying out the method according to the invention, the apparatus 3is moved forwards towards the anus of the carcass of the slaughteredanimal; vacuum is fed to the hollow shaft 27. The pin is, by means ofthe mirror 9, inserted in the anus of the carcass, and the tubular knifeis moved close to the carcass in such a manner that a vacuum can beestablished in the interior of the tubular knife.

Subsequently, the tubular knife is caused to rotate, and, as illustratedin FIG. 2, the knife 34 is then moved into the carcass coaxially withthe rectum. As a result, the rectum is cut free together with asurrounding fatty layer, the reason why the portion cut free is alsoreferred to as the fatty end. The fatty end is diagrammatically shown atthe reference numeral 53 in FIG. 2. While the tubular knife 34 continuesto rotate, the fatty end 53 engages the internal thread 46 on thetubular knife 34 with the result that the suction effect of the vacuumis supported. The oppositely cut external thread 49 on the pin ensuresan additional retaining and guiding of the inner side of the rectumforwards towards the interior of the apparatus 3. The threads 46 and 49inside the apparatus 3 ensure together with the narrowed portion of thepassage 37 about the pin 30 both a good retaining of the fatty end 53and an efficient closing of the rectum in such a manner that nothingsieves out of the rectum.

When the fatty end 53 has been cut completely free and is placed in thebottom of the apparatus 3, the apparatus is pulled substantiallyhorizontally forwards towards the ventral side of the carcass. Duringthe latter movement, the ham 14 is cut in two by means of the knife 51.Subsequently, the apparatus is moved downwards, as shown in FIG. 3,until the rectum 54 is positioned immediately above the guide pipe 11,as also shown in FIG. 3. During the movement from the cutting freelocation and forwards to the area immediately above the guide pipe, theslaughterman must, of course, be very careful to maintain the tubularknife 34 and the pin 30 substantially coaxially with the rectum 54 insuch a manner that the rectum or the fatty end 53 is not pressed outinto contact with the cutting edge 36 and damaged. Attachments 55between the rectum 54 and the carcass are torn loose during the pullingout movement.

When the rectum 54 is positioned above the guide pipe 11 in the positionshown in FIG. 3, the feeding of vacuum is interrupted to the apparatusand a pressurized air valve is opened for a short period. As a resultthe fatty end is released from the apparatus 3 and positions itself insuch a manner that it hangs downwards over the guide pipe 11 and alongthe side of the protecting shield 10 facing away from the carcass.Possible escapes of visceral contents flow down the protecting shieldand are collected in the drain 12.

While the fatty end 53 is hanging over the guide pipe 11, the carcasscan be moved forwards for a cutting free of the remaining intestinalportions without risking escapes of visceral contents coming intocontact with the carcass or the slaughterman.

The tubular knife 34 of the apparatus 3 can remain rotating during themovement from the cutting free location to the release location abovethe guide pipe 11. The retaining is improved by the rotation.

After the cutting free, the apparatus is advanced for sterilization. Theinterior of the apparatus is sterilized by means of hot and cold waterfed through the hose 4.

The apparatus is made of suitable materials easy to clean, and indimensions conventionally used within the field in question. Theinternal thread on the tubular knife has, according to a preferredembodiment of the invention, an inner diameter of 44 mm. The externalthread 49 on the pin 30 is of an outer diameter of 27 mm. Both threadsare trapezoidal with rounded edges and a pitch of 6 mm and a depth of 2mm. The thread 46 on the tubular knife 34 is left-handed.

The outer cylindrical area 43 on the inner side of the tubular knife 34has an inner diameter of 56 mm, whereas the outer part of the pin has adiameter of 12 mm. The length of the conical areas 44 and 47 on thetubular knife 34 and the pin 30, respectively, is approximately 40 mm.

The invention has been described with reference to a preferredembodiment. Many modifications can be carried out without therebydeviating from the scope of the invention. The threads may for instancebe of other shapes beyond the one described, and the protecting shieldwith the associated guide pipe and drain may be shaped in anothermanner.

We claim:
 1. A method of cutting free and removing a rectum of a carcassof a slaughtered animal hanging by its hind legs with its head facingdownwardly, said method comprising the steps of:a) positioning anapparatus including a rotating tubular knife in the vicinity of therectum of the carcass; b) inserting a guiding pin on said apparatus intothe rectum of the carcass coaxially with a main axis of the rectum, saidguiding pin being coaxial with said rotating tubular knife; c) movingsaid rotating tubular knife into the carcass coaxially with the mainaxis of the rectum, thereby cutting the rectum free of the carcass; d)retaining the rectum in said rotating tubular knife; e) pulling therectum free of the carcass toward a ventral side of the carcass in adirection substantially perpendicular to a main axis of the carcass; andf) hanging the rectum downwardly over a side of a protective shield,said side of said shield facing away from the carcass.
 2. A methodaccording to claim 1, further comprising the step of cutting the carcassalong the ventral side starting from a point adjacent the rectum.
 3. Amethod according to claim 1, further comprising the step of cutting thecarcass along the ventral side from a point adjacent where the rotatingtubular knife is moved into the carcass, thereby providing an openingwhich the rectum is pulled through.
 4. An apparatus for cutting free andremoving a rectum of a carcass of a slaughtered animal, said apparatuscomprising:a guiding pin for inserting into the rectum of the carcassand guiding the apparatus as the rectum is cut free and removed, a freeend of said guiding pin being inserted into the rectum; a tubularrotatable knife coaxially surrounding said guiding pin; a cutting edgeprovided on a front edge of said tubular knife; means for creating avacuum suction provided at a rear edge of the tubular knife; and atleast one thread provided on an inner surface of said tubular knife,said at least one thread engaging the rectum and helping to retain saidrectum in said tubular knife.
 5. An apparatus according to claim 4,wherein said inner surface of said tubular knife includes a conicaltransition portion narrowing with increasing distance away from saidcutting edge of said tubular knife.
 6. An apparatus according to claim4, wherein an outer surface of said guiding pin includes at least onethread cut in a direction opposite to said at least one thread on aninner surface of said tubular knife, said at least one thread on saidguiding pin engaging said rectum and helping to retain said rectum insaid tubular knife.
 7. An apparatus according to claim 5, wherein anexternal surface of said guiding pin includes at least one threadarranged in a direction opposite to said at least one thread on saidinner surface of said tubular knife, said at least one thread on saidguiding pin engaging said rectum and helping to retain said rectum insaid tubular knife.
 8. An apparatus according to claim 6, wherein saidguiding pin includes a conical transition portion expanding withincreasing distance away from said free end of said guiding pin andcontinuing into a cylindrical portion including said at least one threadon said external surface of said guiding pin.
 9. An apparatus accordingto claim 7, wherein said guiding pin includes a conical transitionportion expanding with increasing distance away from said free end ofsaid guiding pin and continuing into a cylindrical portion includingsaid at least one thread on said external surface of said guiding pin.10. An apparatus according to claim 4, further comprising:a fixed knifeprovided outside said tubular knife, said fixed knife automaticallycutting the carcass between hind legs of the carcass while the rectum ispulled out of the carcass toward a ventral side of the carcass afterbeing cut free.
 11. An apparatus according to claim 5, furthercomprising:a fixed knife provided outside said tubular knife, said fixedknife automatically cutting the carcass between hind legs of the carcasswhile the rectum is pulled out of the carcass toward a ventral side ofthe carcass after being cut free.
 12. An apparatus according to claim 6,further comprising:a fixed knife provided outside said tubular knife,said fixed knife automatically cutting the carcass between hind legs ofthe carcass while the rectum is pulled out of the carcass toward aventral side of the carcass after being cut free.
 13. An apparatusaccording to claim 7, further comprising:a fixed knife provided outsidesaid tubular knife, said fixed knife automatically cutting the carcassbetween hind legs of the carcass while the rectum is pulled out of thecarcass toward a ventral side of the carcass after being cut free. 14.An apparatus according to claim 8, further comprising:a fixed knifeprovided outside said tubular knife, said fixed knife automaticallycutting the carcass between hind legs of the carcass while the rectum ispulled out of the carcass toward a ventral side of the carcass afterbeing cut free.
 15. An apparatus according to claim 9, furthercomprising:a fixed knife provided outside said tubular knife, said fixedknife automatically cutting the carcass between hind legs of the carcasswhile the rectum is pulled out of the carcass toward a ventral side ofthe carcass after being cut free.
 16. An apparatus according to claim 9,wherein said fixed knife is planar and wherein a cutting edge of saidfixed knife is perpendicular to said tubular knife.
 17. An apparatusaccording to claim 4, further comprising:a shield for preventing fecalmatter contained within the rectum from being directed toward thecarcass after the rectum has been cut free and removed from the carcass;a guide pipe for guiding the rectum toward the shield and for supportingthe shield; and a drain form receiving the fecal matter in the rectum.18. An apparatus according to claim 4, wherein said guiding pin isstationary with respect to said rotating knife.